Turbine control mechanism



Dec. 15, 1931. CAUGHEY 1,836,789

TURBINE CONTROL MEGHANI SM Filed Nov. 26, 1930 FROM RE HEATER Inventor- I Reed J. Caugheg,

y Wm His Attorney.

Patented Dec. 15, 1931 UNITED STATES. PAT

ENT OFFICE REED J. CAUGHEY, or SCHENECYTADY, NEW YORK, Ass-IGNoR. 'ro GENERAL ELECTRIC COMPANY, A CORPORATION on NEW YORK TURBINE CONTROL MECHANISM Application filed November 26, 1930. Serial No. 498,373.

The present invention relates to control mechanisms for elastic fluid turbines, and especially for elastic fluid turbines of the compound type, that is, turbinesof the type comprising a high pressure section and a low pressure section connected in series as regards the flow of elastic fluid.

The object of my invention is to provide an improved control mechanism for a turbine of this type, and for a consideration of what I believe to be novel and my invention, attention is directed to the following specification and the claims appended thereto.

In the drawings, Fig. l is .a diagrammatic view of a compound turbine provided with a control mechanism embodying my invention, and Fig. 2 is adetail view of certain. parts ofthe control mechanism.

Referring to the drawings, 1 indicates the high pressure sectionand 2 the low pressure section of a compound turbine. Elastic fluid is supplied to the high pressure turbine section through a conduit 3 and exhausts therefrom through a conduit 4, and elastic fluid is supplied to the low pressure turbine section through a conduit and exhaust therefrom through the eXhaust conduit 6 to the usual condenser (not shown). Conduit 4 may be connected directly to conduit 5 so that the elastic fluid flows directly from the high pressure turbine section to the low pressure turbine section. Ordinarily, however, theelastic fluid as it flows from the high pressure section to the low pressure section is reheated, and under these circumstances conduit 4 leads to a reheater and conduit 5 leads from the reheater to the low pressure turbine sec tion.

In high pressure conduit 3 is a combined trip and throttle valve 6 valve 7 of suitable type. The combined trip and throttle valve is biased toward closedposition and is held open normally by a latch 8 which engages a catch finger 9. When latch 8 is disengaged from catch finger 9, valve 6 drops to closed position. This is a well-known type of combined trip and throttle valve, and is shown only diagrammatically in the drawings. The latch 8 is adaptedto be moved by a hooklO carried by and a regulating a piston 11 in a cylinder 12. Piston 11 is held normally in the position shown in the drawing by fluid pressure, such as oil pressure, supplied through a pipe 13. Pipe 13 is connected to a reversing valve 14 normally held in the position shown in the drawings against the action of spring 14 by the trip linger 15 of an emergency governor 16. 17- is-a fluid supply pipe for pipe 13, and 18 is a discharge pipe. IVit-h the parts in the position shown in the drawings, fluid is supplied by. pipe 17 through valve 14 to pipe 13 and the cylinder 12. In case of excess speed, the emergency governor moves trip finger 15 away from the end of the stem of valve 14, permitting spring 14 to move the valve to reverse its position, shutting off the supply of oil from pipe 17 to cylinder 12, and relieving the pressure from cylinder 12 through pipe 18. hen this occurs, piston 11 is moved toward the right by spring 19, thus releasing the combined trip and emer gency valve and permitting it to close. This arrangement of emergency control mecha nism is a known one and is shown more fully in the patent to Dryer 1,471,316, patented October 16, 1923. Regulating valve 7 is controlled by a speed governor 20 connected to it through a fluid actuated motor 21 and a usual form of cam actuated mechanism 22. This arrangement oi regulating means for a control valve is well known and is shown only diagrammatically. It is to be taken as typical of any suitable arrangement whereby the speed governor controls the admission of elastic fluid to a turbine. In connection with speed governor 20, 23 indicates diagrammatically the synchronizing spring for the governor, and 24 a reversing motor for adjusting the tension of the spring 23. As is well understood, by adjusting spring 23 the speed governor can be adjusted for the desired turbine speed. The. arrangement so far described is a known one and is to be taken as typical of any suitable regulating and control mechanism for a high pressure turbine section.

In supply conduit 5 of the low pressure turbine is a manually operated shut-off valve 25 and an interceptingvalve .26. Intercept- 111g valve 26 has its stem 27 connected to a piston 28 in a cylinder 29. It is normally biased toward closed position by a spring 30. Connected to the lower end of cylinder 29 is a pipe 30 through which fluid, such as oil, is supplied to cylinder 29 to normally hold intercepting valve 26 open against the action of spring 30. Pipe 3O leads to a reversing valve 31 similar to the reversing valve 14, and having inlet pipe 32 and discharge pipe 32. Inlet pipe 32 connects with a cylinder 33 provided with an admission pipe 34 and a discharge pipe 35. In the cylinder 33 is a valve 36 which in its upper position connects admission pipe 32 to inlet pipe 34 and in its lower position connects admission pipe 32 to discharge pipe 35.

The stem of valve 36 is arranged to be connected by a link 37 to a lever arm 38. The left-hand end of lever arm 38 is connected by a link 39 to the governor lever 40 of speed governor 41 of any suitable type, and provided with a synchronzing mechanism indicated at 42. During normal operation, speed governor 41 is set for a speed slightly higher than normal or synchronous speed, and holds valve 36 in the position shown in Fig. 1, permitting fluid to flow from pipe 34 to pipe 32, through reversing valve 31 and pipe 30 to cylinder 29, thus holding intercepting valve 26 open. The other end of lever 38 is pivoted on a guide bracket 43 carried by the casing of a fluid actuated motor 44.

Connected to the admission end of low pressure turbine section 2 is a conduit 45 through which high pressure elastic fluid may be supplied to the low pressure turbine section. In conduit 45 is a combined trip and throttle valve 46 which may be similar to the combined trip and throttle valve 6 and a regulating valve 47. Combined trip and throttle valve 46 is controlled by a piston and cylinder 48, similar to piston 11 and cylinder 12, connected by a pipe 49 to a reversing valve 50 similar to reversing valves 14 and 31, the reversing valve being controlled by an emergency governor 51. Emergency governor 51 controls also the reversing valve 31. The emergency governor 51 is of the usual eccentric weight type, and in case of excess speed it assumes an eccentric position, striking the trip fingers 52 and 53 thus releasing the reversing valves 50 and 31, permitting them to reverse their positions.

Regulating valve 47 is connected to the piston of fluid actuated motor 44, the connections including a usual arrangement of floating lever 54 and follow-up connection 55. Floating lever 54 comprises two sections 56 and 57, normally held to move with each other by means of a spring 58, thus forming in substance a single lever. The stem of the pilot valve of fluid actuated motor 44 is pivotally connected to the lever section 56. The free end of lever section 57 is adapted to be connected to pivoted arm 38 by means of the link 37, the link being detached from the stem of valve 36 when it is to be attached to the lever section 57. Connected to lever section 56 is a depending arm 59 having a flange 60 at its lower end provided with an opening through which extends loosely the upper end of a stem 61 connected to a piston 62 which slides in a cylinder 6'3. Piston 62 is biased toward the lower end of cylinder 63 by a spring 64. The upper end of the stem 61 is provided with an enlarged head 65 adapted to engage flange 60 when piston 62 moves downward in cylinder 63. The lower end of cylinder 63 is connected by a pipe 66 to reversing valve 50, it being in parallel with the connection to the piston and cylinder 48 which controls combined trip and throttle valve 46.

During normal operation the parts occupy the positions shown in Fig. 1, intercepting valve 26 being open, regulating valve 47 being closed, and the supply of elastic fluid to the turbine sections being under the control of regulating valve 7 and speed governor 20 which control the admission of high pressure elastic fluid to the high pressure turbine section. Speed governor 41 is set for a speed slightly higher than normal operating or synchronous speed but lower than the speed for which emergency governor 51 is set. It thus functions as what is termed usually a preemergency governor, it being inactive at normal or synchronous speed but coming into action at a speed slightly higher than normal but not as high as the speed for which the emergency governor 51 is set.

In case of excess speed of the high pressure turbine unit 1, emergency governor 16, which may be of any suitable type, strikes trip finger 15 thereby releasing reversing valve 14 to disconnect pipe 13 from supply pipe 17 and connect it to discharge pipe 18, thus relieving the fluid pressure on piston 15 and permitting spring 19 to efiectclosing of the combined trip and throttle valve 6*.

In case the speed of low pressure turbine section 2 increases a pre-determined amount, speed governor 41 lowers the right-hand end of governor lever 40 thus lowering valve 36 to disconnect supply pipe 34 from pipe 32 and connect pipe 32 to discharge pipe 35. This relieves the oil pressure under piston 28 by way of pipe 30 reversing valve 31, plpe 32 and pipe 35, thus permitting the intercepting valve 26 to close. If for any reason the speed governor 41 should fail to function and the speed continues to increase, then emergency governor 51 comes into action, striking trip finger 53 and releasing the stem of reversing valve 31, permitting it to reverse and thus connect cylinder 29 to discharge pipe 32 by Way of pipe 30. This relieves the pressure under piston 29 and permits intercepting valve 26 to close. Thus it will be seen that under normal operating conditions intercepting valve 26 is under the control of both speed governor 41 which is set as a pre-emergency governor and emergency governor 51. The use of an intercepting valve is important, because even though combined trip and throttle valve 6 is closed, shutting off the supply of elastic fluid to the high pressure turbine section, this does not immediately shut ofl the supply to the low pressure turbine section 2, because of the considerable amount of elastic fluid contained in the conduits 4 and 5 and the reheater to which they are connected. In the usual installation, the reheater and pipe connections to and from it contain a considerable volume of elastic fluid and enough to cause overspeeding and possibly damage to a low pressure turbine section under emergency conditions if the admission to the low pressure turbine section is not promptly closed.

Regulating valve 47 is normally closed and floating lever 54 is fastened down in a position such that the pilot valve of fluid actuated motor 44 admits actuating fluid above the piston to hold the valve closed, by means of a link 66 which connects lever 54 to a pin on bracket 43, holding the pilot valve in the position shown in Fig. 1. In substance, this serves to lock fluid actuated motor 44 in inoperative position, functioning to hold valve 47 closed.

If for any reason the high pressure turbine section is shut down and it is desired to operate the low pressure turbine section on high pressure elastic fluid, intercepting valve 26 and preferably also hand valve 25 are closed, combined trip and throttle valve 46 is opened, and regulating valve 47 is placed under control of speed governor 41. This latter is accomplished by disconnecting link 37 from the stem of valve 36 and connecting it to the free end of floating lever section 57 as is shown in Fig. 2, link 66 being disconnected from bracket 43 so as to free floating lever 54 for movement. As a matter of convenience, link 66 may be disconnected from bracket 43 and fastened on the side of lever 54 in any suitable way, as is shown in Fig. 2. WVhen link 37 is disconnected from Valve 36 the valve drops to its lowermost position as shown in Fig. 2, thus disconnecting supply pipe 34 from pipe 32 and connecting pipe 32 to discharge pipe 35. The supply of fluid pressure to piston 28 to maintain open the intercepting valve is thus prevented. This effects the result also that if the intercepting valve is not already closed, then the disconnecting of link 37 from valve 36 will automatically effect the closing of the intercepting valve. Speed governor 41 is adjusted by means of its synchronizing mechanism 42 for the desired operating speed and now contro'ls regulating valve 47 in the usual manner to control the admission of high pressure elastic fluid to turbine section 2 in accordance With the speed of turbine section 2. Turbinesection ,2 is now under the control of speed governor 41 and emergency governor 51.

Fluid pressure through pipe 49 normally holds piston 62 in its uppermost position wherein head is spaced away from flange 60. This leaves the governor lever 54 free for movement in the usual way.

In .case emergency governor 51 operates, striking trip finger 52 and releasing reversing valve 50, the reversal of valve ,50 connects pipe 49 to the discharge pi-peof ,the reversing valve thus permitting the fluid pressure to escape from beneath piston 62 and also from behind the piston andcyl-inder 48. lVhen the pressure under piston 62 is released, spring 64 forces piston 62 downward whereupon head 65 engages flange .60 and lowers the pilot valve of uid actuated motor 44 to effect closing of regulating valve 47. In moving downward, lever section 56 alone is moved, the lever section 57 being held stationary by the speed governor 41. The spring 64 is strong enough to overcome 58 which holds lever sections 56 and 57 together, so that the lever section 56 is moved independently of thelever section 57. At the same time, the piston and cylinder device 48 releases the combined trip and throttle valve 46 to permit it to close. It will thus be seen that in case emergency governor '51 operates it eflects closing ofboth the regulating valve 47 and the combined trip and throttle valve 46.

In accordance with the provision of the patent statute, I have described the principleof operation of my invention, together with the apparatus which I now consider to represent the best embodiment thereof; but I desire to have it understood that the apparatus shown is only illustrative and that the invention may be carried out by other means.

What I claim as new and desire ,to secure by Letters Patent of the United States, is:

1. In combination, a high pressure turbine section, a low pressure turbine section, a conduit for conveying elastic fluid from the high pressure turbine section to the low A pressure turbine section, an intercepting valve in said conduit, a conduit for supplying high pressure elastic fluid to the low pressure turbine section, a regulating valve in in said conduit, a conduit for supplying high pressure elastic fluid to the low pressure turbine section, a regulating valve in said last named conduit, a speed governor for the low pressure turbine section, means for oonnect-, ing said speed governor either to the intercepting valve or to the regulating valve, and means which effects closing of the intercepting valve When the connection is transferred from the intercepting valve to the regulating valve.

3. In combination, a high pressure turbine section, a 10W pressure turbine section, a conduit for conveying elastic fluid from the high pressure turbine section to the lOW pressure turbine section, an intercepting valve in said conduit, a conduit for supplying high ressure elastic fluid to the lOW pressure tur- Eine section, a regulating valve in said last named conduit, a speed governor for the low pressure turbine section, an emergency governor for the low pressure turbine section, means connecting both the speed governor and the emergency governor to the intercepting valve, and means for disconnecting the speed governor from the intercepting valve and connecting it to the regulating valve.

4. In combination, a high pressure turbine section, a 10W pressure turbine section, a conduit for conveying elastic fluid from the high pressure turbine section to the lOW pressure turbine section, an intercepting valve in said conduit, a conduit for supplying high pressure elastic fluid to the low pressure turbine section, a regulating valve in said last named conduit, a speed governor for the low pressure turbine section, an emergency governor for the lOW pressure turbine, and means connecting both the speed governor and the emergency governor to the intercepting valve, said speed governor being set for a speed higher than normal speed but below the speed for which the emergency governor is set.

5. In combination, a high pressure turbine section, a 10W ressure turbine section, a conduit for conveying elastic fluid from the hi h pressure turbine section to the low pressure turbine section, an intercepting valve in said conduit, a conduit for supplying high pressure elastic fluid to the low pressure turbine section, a regulating valve in said last named conduit, a speed governor for the lOW pressure turbine section, a fluid actuated motor for the regulating valve including a lever, a control valve for the intercepting valve, and a link for connecting the speed governor either to said lever or to said control valve.

In Witness whereof, I have hereunto set my hand this 25th day of November, 1930.

REED J. CAUGHEY. 

